Chop the ramp leaves, then put in a blender with the water and eggs, working in batches if needed, until you can buzz it up to a smooth puree. Pour the ramp slurry into a bowl and mix well with the flour.
Ideally you’ll let the batter rest for 30 minutes now to autolyze the gluten.
Mix in the salt, mustard and parmesan. Meanwhile, bring a gallon of water to a simmer, and, using a spaetzle maker or a colander, pour the batter through the holes. If you’re using a colander, you’ll want to put a good amount in and press around with a spatula.
Every few minutes, skim the cooked spaetzle off using a strainer or slotted spoon, and transfer to an oiled baking tray, cookie sheet, etc.
When the spaetzle are cooked, rinse them lightly with water to remove starch, then toss with a touch of oil to prevent sticking. From here the spaetzle can be made a day or two in advance. To cook, fry them in butter and toss with herbs.
Notes
I use ramp leaves here, but you can substitute an equal amount of parsley and herbs.